2026 Vol.9 Jun.N03

• Title: Study on residual strength performance of recycled concrete after fire based on thermal-mechanical coupling finite element analy
• Name: Rui Guo
• Company: Jilin Jianzhu University,Changchun,130119,China
• Abstract:

  【Objective】 To explore the synergistic deterioration mechanism of recycled aggregate replacement rate and fire temperature on the mechanical properties of recycled concrete after disaster, and to quantify the attenuation law of residual compressive strength and elastic modulus after fire cooling. 【Method】 Four groups of standard cubic specimens with 100mm replacement rate of recycled coarse aggregate were prepared, and the thermal and mechanical parameters were calibrated in the range of 20℃~900℃ by muffle furnace, pressure testing machine and SEM. A partitioned three-dimensional finite element model was constructed. The matrix mesh size was 5mm and the aggregate interface was densified to 2 mm. The temperature-displacement synchronous iterative thermal-mechanical coupling algorithm was adopted, and four constant-temperature fire conditions of 200℃, 400℃, 600℃ and 800℃ were set. Sixteen numerical examples were simulated to simulate the whole process of heating and insulation, natural cooling and static compressive loading, and residual strength, elastic modulus and damage factor were extracted for analysis. 【Result】 Under the condition of constant fire temperature, the higher the replacement rate of recycled aggregate, the more obvious the attenuation of mechanical properties after disaster. At 800℃, the residual compressive strength of the specimen with 0% substitution rate is 7.25MPa, and the 70% substitution rate is only 2.68MPa, with a difference of 4.57MPa；. When the temperature exceeds 400℃, the elastic modulus decreases in a cliff-like manner. The performance of the single substitution rate specimen continues to deteriorate with the increase of fire temperature, and the strength residual rate of the 50% substitution rate specimen is 90.66% at 200℃ and only 12.74% at 800℃. The sensitivity of elastic modulus to high temperature damage is higher than that of compressive strength, and the internal double aggregate interface is the damage priority development area. 【Conclusion】 The weak structure of primary pores and double-layer interface of recycled aggregate is the core inducement of accelerated mechanical properties decay at high temperature, and 400~600℃ is the critical interval of sudden change of bearing capacity and stiffness of recycled concrete.

  
  

• Keyword: thermal-mechanical coupling; Finite element analysis; Recycled concrete; Residual strength; Performance research;
• DOI: 10.12250/jpciams2026090601
• Citation form: Rui Guo.Study on residual strength performance of recycled concrete after fire based on thermal-mechanical coupling finite element analysis[J]. Computer Informatization and Mechanical System,2026,Vol.9,pp.

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